`right_null` errors when `trunc` is provided

[ogauthe]

Hi! I found that rightnull has an issue on a TensorMap when trunc is provided.

using TensorKit

m1 = ones((2,2))
m2 = id(ℂ^2)
right_null(m1; kind=:svd, trunc=(;atol=1e-10))  # Ok
right_null(m2; kind=:svd)  # Ok
right_null(m2; kind=:svd, trunc=(;atol=1e-10))  # MethodError

ERROR: MethodError: no method matching size(::TensorMap{Float64, ComplexSpace, 1, 1, Vector{Float64}}, ::Int64)
The function `size` exists, but no method is defined for this combination of argument types.

Closest candidates are:
  size(::BitVector, ::Integer)
   @ Base bitarray.jl:107
  size(::LinearAlgebra.Hessenberg, ::Integer)
   @ LinearAlgebra ~/.julia/juliaup/julia-1.12.1+0.x64.linux.gnu/share/julia/stdlib/v1.12/LinearAlgebra/src/hessenberg.jl:412
  size(::Tuple, ::Integer)
   @ Base tuple.jl:31
  ...

Stacktrace:
 [1] truncate(::typeof(right_null!), ::Tuple{…}, strategy::MatrixAlgebraKit.TruncationByValue{…})
   @ MatrixAlgebraKit ~/.julia/packages/MatrixAlgebraKit/xv5dv/src/implementations/truncation.jl:24
 [2] right_null_svd!(A::TensorMap{…}, Nᴴ::TensorMap{…}, alg::@NamedTuple{}, trunc::@NamedTuple{…})
   @ MatrixAlgebraKit ~/.julia/packages/MatrixAlgebraKit/xv5dv/src/implementations/orthnull.jl:290
 [3] #right_null!#250
   @ ~/.julia/packages/MatrixAlgebraKit/xv5dv/src/implementations/orthnull.jl:266 [inlined]
 [4] right_null!
   @ ~/.julia/packages/MatrixAlgebraKit/xv5dv/src/implementations/orthnull.jl:255 [inlined]
 [5] right_null!(A::TensorMap{Float64, ComplexSpace, 1, 1, Vector{…}}; kwargs::@Kwargs{kind::Symbol, trunc::@NamedTuple{…}})
   @ MatrixAlgebraKit ~/.julia/packages/MatrixAlgebraKit/xv5dv/src/interface/orthnull.jl:216
 [6] right_null!
   @ ~/.julia/packages/MatrixAlgebraKit/xv5dv/src/interface/orthnull.jl:215 [inlined]
 [7] #right_null#227
   @ ~/.julia/packages/MatrixAlgebraKit/xv5dv/src/interface/orthnull.jl:219 [inlined]
 [8] top-level scope
   @ REPL[5]:1
Some type information was truncated. Use `show(err)` to see complete types.

julia v"1.12.1"
TensorKit v0.15.3